1. Field of the Invention
The invention relates to a facsimile hardware device and more particularly to a facsimile jack, connected between a facsimile machine and a telephone line interface, which is capable of controlling a transmission route of a facsimile transmitted from the facsimile machine.
2. Description of the Related Art
Conventionally, facsimile data transmissions are conducted entirely through voice grade, analog telephone lines. A typical facsimile transmission route is shown in FIG. 1 A source facsimile machine 10 dials a phone number of a destination facsimile machine 12. The call is routed through a telephone jack 20 to a local exchange carrier at a central office (LEC CO) 30. Subsequently, a connection is made from the LEC CO 30 to a local interexchange carrier's point of presence (IXC POP) 40. The local IXC POP 40 makes a connection through a long distance carrier facility 50 to a destination IXC POP 42 which in turn makes a connection to a destination LEC CO 32. The destination LEC CO 32 then calls the phone number of the destination facsimile machine 12. Once the destination facsimile machine 12 answers, an end-to-end connection is established between the two facsimile machines 10, 12. The appropriate facsimile session setup is then performed by the two facsimile machines 10, 12, and this is followed by the facsimile data transmissions. Upon completion of the facsimile data transmissions, the facsimile machines hang up and the connection is terminated
In the conventional system illustrated in FIG. 1, when one facsimile machine dials another, a circuit-like connection is created between the two machines Data is transmitted between the machines in real-time. In other words, there is little delay from when the source facsimile machine 10 sends data to when the destination facsimile machine 12 receives the data.
Further in the conventional system, telecommunications services (phone lines, etc.) used for facsimile transmissions, and their associated cost structure, are formally defined by the carrier in a document called a tariff. Tariffs are filed for approval by state regulatory commissions and/or the Federal Communication Commission (FCC).
There are also store and forward services available for transmitted facsimiles. With store and forward, a facsimile is generally transmitted to a local vendor with information about the final destination. The local vendor then takes responsibility for delivering the facsimile. Such services are not real-time in that there is no circuit-like connection between the source and destination facsimile machines. In such systems, the facsimile transmission is usually sent at a later time when the rates are less. A disadvantage of such systems is that in the event a facsimile cannot be delivered to the destination facsimile machine, there may be no reliable way of notifying the user of the source facsimile machine that the facsimile has not been delivered. Important facsimile transmissions requiring immediate delivery and confirmation of receipt generally cannot be sent through such systems.
Another conventional way of reducing costs of data transmission including, for example, facsimile data, voice data, and modem data, is to use alternate communication services, such as a dedicated telephone lines such as a Wide Area Telephone Service (WATS) line or a Virtual Private Network (VPN) line. Alternatively, telephone companies offer a variety of overlapping discount schedules which could be utilized to minimize costs for a particular transmission. A disadvantage of using such alternate communication services is that a user has to be aware of a multitude of telephone number, access codes, and rate schedules.
Auto-dialers may also be used to reroute calls to a voice carrier based on broad categories, long distance, intra-lata, etc. They are however unselective in that, if a call is long distance, it is routed regardless of the destination. Also, these devices do not reroute if the original target is busy or unavailable. Lastly, these device do not exchange information up to or down from the facility to which they connect nor do they exchange signalling or other forms of communication.
Moreover, facsimile transmissions today are accomplished through the use of analog grade circuits. While almost all telephone systems have upgraded their backbone and main transport facilities from an analog to a digital infrastructure, the primary interface to the customer/end user is still an analog line. The telephone companies perform an analog to digital and then digital to analog conversion to merge these two transport mediums. Facsimile transmissions start out, internally to the facsimile device, as digital data which is then modulated and overlayed with a protocol for transport over an analog medium. In theory it is possible for an analog line to carry 56 Kbps of information. In order to support an end to end circuit mode connection, the digital infrastructure must allocate or make available this much bandwidth. When the analog facsimile transmission is demodulated and the protocol removed, a maximum data transfer rate of 28.8 Kbps can be supported. Usually, the transmission requires only 9.6 Kbps or less of bandwidth. As a consequence, when a facsimile is sent over a voice grade circuit through the network's digital transmission facilities, most of the bandwidth is not utilized even though it is being paid for.
An example of a digital network, access to which is still made through voice grade lines, is shown in FIG. 2, and corresponds to a system recommended in a document published by The International Telegraph and Telephone Consultative Committee (CCITT). In the CCITT system, data is transmitted digitally between a source facsimile packet assembly/disassembly facility (FPAD) 44 and a destination FPAD 46 through a Packet Switched Public Data Network (PSPDN) 51. The access to either FPAD 44 or 46 is still made through its respective General Switched Telephone Network (GSTN) 31 or 33. The CCITT system has some technical characteristics, however, which make it unattractive, particularly for facsimile transmissions. They are:
1. It runs on X.25 protocol which significantly increases the length of call.
2. It does not guarantee delivery of data.
3. It has a variable delay in delivery of communicated packets.
4. It does not accommodate switched analog access lines.